As shown in FIG. 1 in case of the general construction machine, an operation time of a machine is calculated using an output from an alternator connected mechanically with an engine. That is, a conventional construction machine recognizes the operation of a machine only when an engine is operated, and sends the operation time of the machine to a display. An operator confirms the operation time displayed as described above for the maintenance of the components of the machine.
When such a system is applied for an electric hybrid construction machine as shown in FIG. 2, it is impossible to calculate accurately the operation time of component which is not directly associated with an engine, since the electric hybrid construction machine can be operated only by an energy stored in ESS (Energy Storage System) that is independent of the operation state of the engine. For example, in case of the single operation of driving only EMI (Electrical Motor), it is impossible to calculate the operation time of the individual work device (component) using the general calculation method of FIG. 1.
Consequently, a conventional technique makes it difficult to predict the individual operation time of the respective main component and manage the maintenance period of the respective component. Accordingly, a conventional technique makes it difficult for an operator to efficiently maintain the components, and an operator may miss the proper time of replacing the components. This causes the operator the unnecessary maintenance costs, and the machine that has not been properly maintained causes trouble or requires the additional maintenance, which lowers the availability of the machine.